Check if sys_info is null

notebook/static/notebook/js/about.js

@@ -8,19 +8,27 @@ require([
     'use strict';
     $('#notebook_about').click(function () {
         // use underscore template to auto html escape
-        var text = 'You are using Jupyter notebook.<br/><br/>';
-        text = text + 'The version of the notebook server is ';
-        text = text + _.template('<b><%- version %></b>')({ version: sys_info.notebook_version });
-        if (sys_info.commit_hash) {
-            text = text + _.template('-<%- hash %>')({ hash: sys_info.commit_hash });
+        if (sys_info) {
+          var text = 'You are using Jupyter notebook.<br/><br/>';
+          text = text + 'The version of the notebook server is ';
+          text = text + _.template('<b><%- version %></b>')({ version: sys_info.notebook_version });
+          if (sys_info.commit_hash) {
+              text = text + _.template('-<%- hash %>')({ hash: sys_info.commit_hash });
+          }
+          text = text + _.template(' and is running on:<br/><pre>Python <%- pyver %></pre>')({ 
+            pyver: sys_info.sys_version });
+          var kinfo = $('<div/>').attr('id', '#about-kinfo').text('Waiting for kernel to be available...');
+          var body = $('<div/>');
+          body.append($('<h4/>').text('Server Information:'));
+          body.append($('<p/>').html(text));
+          body.append($('<h4/>').text('Current Kernel Information:'));
+          body.append(kinfo);
+        } else {
+          var text = 'Could not access sys_info variable for version information.';
+          var body = $('<div/>');
+          body.append($('<h4/>').text('Cannot find sys_info!'));
+          body.append($('<p/>').html(text));
         }
-        text = text + _.template(' and is running on:<br/><pre>Python <%- pyver %></pre>')({ pyver: sys_info.sys_version });
-        var kinfo = $('<div/>').attr('id', '#about-kinfo').text('Waiting for kernel to be available...');
-        var body = $('<div/>');
-        body.append($('<h4/>').text('Server Information:'));
-        body.append($('<p/>').html(text));
-        body.append($('<h4/>').text('Current Kernel Information:'));
-        body.append(kinfo);
         dialog.modal({
             title: 'About Jupyter Notebook',
             body: body,